Leveling device for sheet material feeding mechanism

ABSTRACT

A levelling device for cardboard sheet material and the like located at a feed station of a sheet material processing station to assure that the forward marginal area of each sheet lies flat on the feed surface of the processing machine. It is particularly concerned with sensing whether both the forward edge of a sheet as well as a portion of the sheet spaced a short distance rearwardly of the forward edge are lying flat on the feed surface; and if not, raising or lowering the rear edge of the sheet until the forward marginal edge is lying flat on the feed surface.

United States Patent [191 m1 3,715,1 16 Salvade 1 Feb. 6, 1973 LEVELING DEVICE FOR SHEET f r n Ci ed MATERIAL FEEDING MECHANISM UNITED STATES A T 1 inventor: Genflam Salvade, pfeverenges, 3,476,380 ll/l969 Calistrat ...271 44 A Switzerland 3,490,763 1/1970 Darwin ..27l/44 A [73] Assignee: J. Bobst & Fils, S.A., Prilly, Switzer- Primary Examiner Richard E Alegerter land Attorney-Carlton Hill et al. [22] Filed: Oct. 15, 1971 [57] ABSTRACT [2|] Appl. No.: 189,510

A levelling device for cardboard sheet material and the like located at a feed station of a sheet material [30] Foreign Application Priority Data processing station to assure that the forward marginal area of each sheet lies flat on the feed surface of the Oct. 20, 1970 Switzerland ..l5505/7O processing machine It is particularly concerned with sensing whether both the forward edge of a sheet as 52 us. Cl. ..271/44 A as a Portion of the Sheet Spaced distance [5]] Int Cl B6Sh 1/06 rearwardly of the forward edge are lying flat on the 58 Field of Search .......271/44 R, 44 A feed Surface and ra'smg Wermg the rear edge of the sheet until the forward rnarginal edge is lying flat on the feed surface.

8 Claims, 4 Drawing Figures PATENTEUFEB B1575 SHEET 10F 2 INVENTOR. Gsxmara 50/7/67 a e ATTYS.

PATENTEDFEB 6 I975 3.715116 SHEET 20F 2 COMPRESSED AI R Fig.3

INVENTOR. Glenna/"re 622/7/06/6 AT T vs LEVELING DEVICE FOR SHEET MATERIAL FEEDING MECHANISM CROSS-REFERENCE TO RELATED APPLICATIONS This invention is not believed to be related to any application of applicant or any application assigned to the same assignee as the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention In the field where a press or other machine processes relatively large sheets of cardboard or other similar relatively stiff but flexible material, it is desirable that the forward marginal portion of each sheet when it arrives at the feed station lie relatively flat on the feed surface so as to be in a position to be properly advanced into the machine. It has been found that occasionally, a sheet will be in a slightly concave upwardly condition when it arrives at the feed station, thus causing the forward edge of the sheet to be raised off of the feed surface while a marginal portion slightly rearwardly of the forward edge is on the feed surface. Conversely, it has also been found that sometimes the sheet is curved convexly upwardly so that the forward edge is resting on the feed surface, but a marginal portion of the sheet slightly rearwardly of the forward edge is raised off of the feed surface. The purpose of the present invention is to overcome this difficulty and to cause the forward marginal portion of each sheet to lie flat on the feed surface immediately after arriving there.

2. Description of the Prior Art Applicant knows of no prior art which specifically relates to the present invention.

SUMMARY OF THE INVENTION The present invention provides an arrangement for overcoming the difficulties above referred to and for causing the forward marginal portion of each sheet to lie flat on the feed surface immediately prior to being advanced into a machine for processing. The novel apparatus for performing this function includes supporting each sheet at the feed station on forward support members which are fixed and which lie in the plane of the feed members of the machine; and to supporting the rear marginal portion of each sheet on a movable member or members which are arranged to be moved upwardly and downwardly to vary the height of the rear marginal edge of the sheet with respect to the forward supporting surface. Sensing means is provided in the forward support'surface to detect whether either the extreme forward edge of the sheet is off of the support surface or whether the marginal portion spaced slightly rearwardly of the forward edge is off of the support surface. When the extreme forward edge of the sheet is detected as being off of the support surface the rearward edge supporting member is raised, thus to rock the sheet on the support surface to lower theforward edge of the sheet. When the marginal portion, spaced slightly rearwardly of the forward edge, is detected as being off of the support surface, the rearward edge supporting means is lowered to bring the marginal portion spaced slightly rearwardly of the forward edge, down to contact with the supporting surface.

Feed devices of the reciprocable shuttle type having suction cups for grasping the under surface of a sheet are known in the prior art. In one of such feed devices, the forward marginal portion of the lower sheet of a stack rests on guides located in the plane of the feed plate or shuttle. The feed plate, after grasping the sheet, moves it forwardly into the machine. The feed plate then moves rearwardly to grasp and feed the next sheet of the stack. A problem in this type of feed mechanism is that unless the sheet to be introduced or conveyed lies practically flat on the feed plate, it cannot be inserted below feed gauge of the processing machine.

The novel device of the present invention is designed to coact with and form an integral part of a feeding device of the above type which, when embodied in the feeding device, overcomes the aforesaid difficulties of the past.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a feed mechanism illustrating different positions a sheet might occupy on such a device;

FIG. 2 is a schematic plane view of a feed mechanism which embodies the novel teachings of the present invention; and

FIG. 3 is a section along line IIIIII of FIG. 2.

FIG. 4 diagrammatically represents a conventional type pneumatic element used in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 of the drawings diagrammatically illustrate a device for feeding sheets into a machine for processing them. The sheets are relatively large and are somewhat stiff, but nevertheless flexible, such as cardboard sheets, which are processed in a die cutting and creasing machine. The device illustrated includes two front supports or rails l and 2 which are laterally spaced apart. A feed plate or shuttle 3 is mounted for back and forth movement andas shown includes three sections, one lying between the supports 1 and 2 and the others lying on the outer sides. of the supports. The upper surface of the supports and the upper surface of the feed plate lie approximately in the same plane. -As the feed plate moves forwardly (i.e., to the left in FIG. I), a sheet is advanced below the gauge 4 into the processing machine (not shown) as indicated by the arrow A. The rear marginal portion of the sheet before being advanced into the processing machine rests on rear supports which comprise a plurality of arms 5 rigidly carried on a rotatable shaft .6. The outer ends 7 of the arms 5 are provided with rollers 8 upon which the rear portion of a sheet F rests. When the shaft 6 is rocked in a clockwise direction as viewed in FIG. I, the arm 5 is moved to the position as shown at 5. When the shaft 6 is rocked in a counterclockwise direction as viewed in FIG. 1, the arm 5 is moved to the position as shown at 5". t

FIG. 1 diagrammatically shows three possible positions of a sheet whose front marginal portion is supported on the front supports 1 and 2 and whose rear marginal portion is supported on the rollers 8 carried by the arms 5. In the position shown as F,, the sheet is in a normal position with thefront marginal portion of the sheet lying flat on the horizontal portion of the front supports 1 and 2. No correcting adjustment is required in this position. If the sheet is in an upwardly convex position, as diagrammatically indicated at F the extreme front edge of the sheet rests on the front supports 1 and 2 and the rear edge is carried on the rollers 8 of the arms 5. The front marginal portion of the sheet, however, does not lie flat on the front supports 1 and 2, and, therefore, in accordance with the teachings of the present invention, the rear edge of the sheet is lowered until the entire front marginal portion of the sheet lies flat on the supports 1 and 2, as indicated at F' This is accomplished by rocking the shaft 6 in a counterclockwise direction to lower the outer end of the arm to the position indicated at 5".

If the sheet lies on the front supports 1 and 2 in an upwardly concave position so that it is supported at its rear edge by the rollers 8 and at an inwardly spaced point of the front marginal portion as shown at F the extreme front edge of the sheet is spaced upwardly from the front supports 1 and 2. To overcome this situation and cause the front marginal portion to lie flat on the supports 1 and 2, the shaft 6 is rocked in a clockwise direction to lift the rear marginal portion of the sheet from the position shown at I to that shown at F This causes the entire front marginal portion of the sheet to rest flat on the supports 1 and 2.

When the sheet has its front marginal portion lying flat on the front supports 1 and 2, it is in a position to be seized by suction cups 3 of the, feed plate 3 and advanced below the gauge 4 into the processing machine.

In the present invention, means is provided to sense whether the front edge of the sheet is lying flat on the supports 1 and 2 and whether the rearward part of the front marginal portion is lying flat on the front supports 1 and 2. Should the sensing mechanism determine that the front edge of the sheet is not lying on the front supports 1 and 2, motor driven means rocks the shaft 6 in a clockwise direction (as viewed in FIG. 1) until the front edge comes to rest on the front supports 1 and 2.

If the sensing means determines that the rearward part of the front marginal portion of the sheet is not lying flat on the front supports 1 and 2, the motor driven means is actuated to rotate the shaft 6 counterclockwise until the rearward part of the front marginal portion comes down against the front supports 1 and 2.

FIG. 3 diagrammatically illustrates one form of sensing means and motor driven actuating means for accomplishing the above end. FIG. 3 is a diagrammatic sectional view along the line III-III of FIG. 2. While only front support 1 appears in this view due to the location of the section taken, it will be understood that similar structure is provided for the front support 2. As will appear from the examination of FIG. 3, two tubes 11 and 12 are provided, one adjacent the front edge of the sheet F, and the other adjacent the rearward part of the front marginal portion of the sheet F. The tubes 11 and 12 are in communication with a compressed air source 13 through conduits 14, 14' and 14". The upper surface of the support 1 opposite the ends of the tubes 11 and 12 is countersunk as at 21 and 22. The lower ends of tubes 11 and 12 are closed, but smaller tubes extend up through the closed lower ends of the main tubes 11 and 12 and terminate below the surface of the front support 1 within the countersink. It willbe noted that the main tubes 11 and 12 also terminate below the upper surface of the front support 1, thus leaving a chamber defined by the countersink below the upper surface of the front support 1 when a sheet is lying flat on the support. The lower ends of the inner tubes 15 and 16 connect tubes 19 and 20. The lower ends of the tubes 19 and 20 communicate with electropneumatic members 17 and 18 which are arranged to actuate switches (not shown). A reversible electric motor 25 is provided to drive a worm 9. The worm 9 is in mesh with a worm wheel 10, fixed to the shaft 6. When the motor is rotated in one direction, the shaft 6 is rocked in one direction, and when the motor 25 is driven in the opposite direction, the shaft 6 is rotated in the opposite direction.

From an inspection of FIG. 3, it will be observed that when the sheet is in the position as shown, compressed air from the compressed air source 13, causes the air pressure in the tube 20 to be at a higher level than that in the tube 19. It is to be understood that under this circumstance, electric motor 25 is driven in a direction to rock the arm 5 upwardly until the forward edge of the sheet F closes off the countersink 23 of the oriface 21. The reverse action takes place when the sheet F lies in a position where the oriface 21 is closed off but where the oriface 22 is exposed. The electro-pneumatic members l7 and 18 under such a circumstance, closes an electric circuit to cause the motor 25 to be operated in a reverse direction, and thus lower the arm 5.

When the sheet F lies flat on the support 1 in the original instance, the air pressure in the tubes 19 and 20 is the same, and the motor circuits is not closed for operation in either direction.

Of course, when there is no sheet present above the nozzles 11 and 12, there is also a balance of pressure in conduits 19 and 20, and hence no actuation of the electric motor 25.

The electro-pneumatic members 17 and 18 may be of any conventional form. They include switches for electrical connecting motor 25 to a suitable source of electric power through electric lines 26. When the member 17 is actuated by a drop in pressure the motor is energized through lines 24 by connection to lines 26 with polarity necessary to drive motor 25'to raise arms 5. When the member 18 is actuated by a drop in pressure relative to that in member 17, the motor is energized through lines 24 and lines 26 with a polarity necessary to drive motor 25 to lower arms 5.

One conventional form of electro-pneumatic element of the type diagrammatically represented at 17 and 18 is a device available on the market as a Luftruckstauaggregat, manufactured by Bircher, Schaffhausen, Switzerland.

FIG. 4 exemplifies such a structure. The electropneumatic member 17 includes a housing 26 having a diaphragm 27 mounted therein which separates the housing 26 into a chamber 28 and a chamber 29. The chamber 28 opens into the tube-19 while the chamber 29 opens to the atmosphere through a tube 30. An adjustable stop 31 extends through the wall of the housing 28 to limit the movement of the diaphragm 27 in one direction. The adjustable abutment 31 acts as a contact and is connected to an electric line 32. The diaphragm 27 carries an electrical contact 33 which is connected through the line 34 to a solenoid 35 which actuates a switch 36. When the pitot-static tube has nothing obstructing ists upper end, the air from compressed air source 13 flows rapidly by and causes a reduction of pressure in the chamber 28. This causes movement of the diaphragm 27 to move contact 33 into closing engagement with contact 31 and the switch 36 is then in its closed position. When the upper end of the pitotstatic tube 19 is closed off or restricted such as by having a sheet passed within five millimeters or less of its upper end, there is no appreciable reduction of air pressure in the chamber 28 and the diaphragm 27 moves to its central position within the housing 26. The contacts 33 and 31 are thus separated, the solenoid is deenergized, and under a suitable bias not shown the switch 36 moves to its open position. Device 18 is similar to device 17.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

1 claim as my invention:

1. A levelling device for sheet material being fed one sheet at a time into a processing machine comprising fixed front support means for supporting the forward marginal portion of a sheet, rear support means for supporting the rear marginal portion of said sheet, means for vertically moving said rear support means, first sensing means for detecting whether the forward marginal portion of said sheet adjacent the forward edge of said sheet is resting on said forward support means, second sensing means spaced rearwardly of said first sensing means for detecting whether a second portion of said forward marginal portion of said sheet spaced rearwardly of said forward edge of the said sheet is resting on said forward support means, and means responsive to said first and said second sensing means for vertically adjusting the height of said rear support means.

2. A levelling device according to claiml, which includes means for raising said rear support means when said first sensing means senses the fact that the forward edge of said sheet is not resting on said front supporting means.

3. A levelling device according-to claim 1, which includes means for lowering said rear support means when said second sensing means senses the fact that said second portion of said forward marginal portion of said sheet is not resting on said front supporting means.

4. A levelling device according to claim 1, in which said means for vertically moving said rear support means is deenergized when said first and second sensing means give the same response.

5. A levelling device for a material in sheets adapted for use at a feed station where sheets are fed into a machine for processing them, comprising fixed front support means intended to support the lower sheet of a stack along a first marginal area, rear, vertically adjustable support means for supporting a second marginal area opposite said first zone, control means for causing the rear support means to rise or descend, said control means comprising at least one group of at least two detectors placed one behind the other in said front support means, motor means to cause the rear support means to rise or descend, and an energizing circuit for said motor means controlled by said control means to connect said motor means to said energizing circuit to selectively cause said motor to raise or lower said rear support means depending on the detection made by said detectors.

6. A device according to claim 5, whereby the detectors of each group comprise air nozzles which have their openings in a surface located behind the plane of said front support means, a compressed air source connected to said nozzles, sensing means connected to said nozzles for controlling said motor means as a function of said pressure which varies according to the closing degree of the discharge openings of the nozzles in rela tion to the lower sheet of the stack.

7. A device according to claim 5, wherein the rear support means comprises rollers carried on arms fixed to a rotatable shaft, the position in. height of said rollers being adjustable by rotating said shaft through a limited angle.

8. A device according to claim 7, in which said arms are adjustable in angular position and are laterally displaceable. 

1. A levelling device for sheet material being fed one sheet at a time into a processing machine comprising fixed front support means for supporting the forward marginal portion of a sheet, rear support means for supporting the rear marginal portion of said sheet, means for vertically moving said rear support means, first sensing means for detecting whether the forward marginal portion of said sheet adjacent the forward edge of said sheet is resting on said forward support means, second sensing means spaced rearwardly of said first sensing means for detecting whether a second portion of said forward marginal portion of said sheet spaced rearwardly of said forward edge of the said sheet is resting on said forward support means, and means responsive to said first and Said second sensing means for vertically adjusting the height of said rear support means.
 1. A levelling device for sheet material being fed one sheet at a time into a processing machine comprising fixed front support means for supporting the forward marginal portion of a sheet, rear support means for supporting the rear marginal portion of said sheet, means for vertically moving said rear support means, first sensing means for detecting whether the forward marginal portion of said sheet adjacent the forward edge of said sheet is resting on said forward support means, second sensing means spaced rearwardly of said first sensing means for detecting whether a second portion of said forward marginal portion of said sheet spaced rearwardly of said forward edge of the said sheet is resting on said forward support means, and means responsive to said first and Said second sensing means for vertically adjusting the height of said rear support means.
 2. A levelling device according to claim 1, which includes means for raising said rear support means when said first sensing means senses the fact that the forward edge of said sheet is not resting on said front supporting means.
 3. A levelling device according to claim 1, which includes means for lowering said rear support means when said second sensing means senses the fact that said second portion of said forward marginal portion of said sheet is not resting on said front supporting means.
 4. A levelling device according to claim 1, in which said means for vertically moving said rear support means is deenergized when said first and second sensing means give the same response.
 5. A levelling device for a material in sheets adapted for use at a feed station where sheets are fed into a machine for processing them, comprising fixed front support means intended to support the lower sheet of a stack along a first marginal area, rear, vertically adjustable support means for supporting a second marginal area opposite said first zone, control means for causing the rear support means to rise or descend, said control means comprising at least one group of at least two detectors placed one behind the other in said front support means, motor means to cause the rear support means to rise or descend, and an energizing circuit for said motor means controlled by said control means to connect said motor means to said energizing circuit to selectively cause said motor to raise or lower said rear support means depending on the detection made by said detectors.
 6. A device according to claim 5, whereby the detectors of each group comprise air nozzles which have their openings in a surface located behind the plane of said front support means, a compressed air source connected to said nozzles, sensing means connected to said nozzles for controlling said motor means as a function of said pressure which varies according to the closing degree of the discharge openings of the nozzles in relation to the lower sheet of the stack.
 7. A device according to claim 5, wherein the rear support means comprises rollers carried on arms fixed to a rotatable shaft, the position in height of said rollers being adjustable by rotating said shaft through a limited angle. 